Concidering we are using the unstable ones (L1 & L2). Is there a reason we aren’t using the only two stable ones for satellites?
In: Planetary Science
They are far away and there is no good use case for them at the moment. In the future they might be used for relay satellites to communicate with planets that are behind the Sun (as seen by Earth). With Mars rovers this isn’t a big deal – you program them to just wait until communication works again – but crewed missions are safer with uninterrupted communication in case they need assistance from Earth.
The instability of L1 and L2 isn’t an issue over the typical lifetime of spacecraft (~5-20 years). The points are close to Earth and they are great spots to observe the Sun and Earth (L1) or things far away, undisturbed by Earth and the Sun (L2).
Due to the natural stability of L4 and L5, it is common for natural objects to be found orbiting in those Lagrange points of planetary systems. Objects that inhabit those points are generically referred to as ‘trojans’ or ‘trojan asteroids’. The name derives from the names that were given to asteroids discovered orbiting at the Sun–Jupiter L4 and L5 points, which were taken from mythological characters appearing in Homer’s Iliad, an epic poem set during the Trojan War. Asteroids at the L4 point, ahead of Jupiter, are named after Greek characters in the Iliad and referred to as the “Greek camp”. Those at the L5 point are named after Trojan characters and referred to as the “Trojan camp”. Both camps are considered to be types of trojan bodies.
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